Most rocks sink in water due to their higher density, but some rare rocks can resist gravity due to their low density reached under critical condition
Pumice, a lightweight volcanic rock created by fast cooling gas-filled lava, is known as the champion of floating rocks.
Despite being less dense than water, pumice can hold trapped air for extended periods due to its intricate internal pathways.
When rare rocks with high iron concentrations, such as scoria, mix with water, they emit gas bubbles, lowering their density and creating buoyancy.
Iron in scoria can react with water to produce hydrogen gas, causing a temporary lift until the gas escapes.
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